My F150 was a flex-fuel, E85 compatible vehicle. From research it sounds like in general E85 is the equivelant of a higher octance fuel and can produce higher horsepower numbers. However, like most things, there is a trade-off. E85 is about 20-30% less fuel efficient, which means less miles per gallon.

I tried it a couple of times last summer to see what the difference was. From the butt-dyno, and remember this was in a 5000lb truck, there was a little more bottom end grunt but otherwise it drove and felt the same. However, I saw a 33% reduction in my fuel milage!! At that time, the cost of E85 was about 25% less then 87 octane (which I was running in the truck) but at 33% reduction in mileage, it actually cost more per mile to run E85, so I switched back.

If you are looking for pure performance, which I think both Ted and Randy are after then efficiency loss is negligible. Another thing to consider, flex fuel vehicles are gasoline are less efficient with E85 because of the compensation and switching between programs. In the end they are still gasoline tuned vehicles with the ability to safely run E85.

I think if you properly tune a vehicle to run only E85, it will have less of a drop off on the MPGs. As always YMMV, but I thin the average drop is about 10-15%. If you usually fill up with premium it is not a big deal because the price disparity per gallon is like ~$1.30. So if I lost 3 or 4 mpg I would still come out ahead.

However, vehicles running regular unleaded or E85 may not really have a savings. I am not an expert on the subject, but am learning as much as I can for many reasons. Best of all, Coors has tossed their hat in the ring for creating Ethanol from their byproducts.

I am less concerned now that I won't have a 62 mile per day commute ....it would have been a good conversion for the scoobie. But if mileage drops, might not be worth the savings since I put in low oct fuel anyway.

Exactly. There is a local company who is waiting for (and expecting) approval from the EPA for a conversion kit. It is basically a second ECU. I'm, not sure how they are going to get away with it without extra O2 sensors and different injectors. The kit's should be somewhat affordable and will be more or less wire in and play.

Again, my input is, if you drive a car running on regular gas anyway, it's probably not worth it, especially if there is not a station near by selling it.

It kind of irks me that all the people upset about fuel prices run out to buy flex fuel vehicles. Including people with paid off vehicles! Go out and get a big car payment, and get a vehicle that runs on any grade fuel, then find you aren't really saving anything. If E85 were like $0.89/gallon I would say go for it!

well, needless to say being able to ruin in race mode for the past couple of weeks has been fun for sure (and mathmatically, current 91 prices versus my increased consumption of e85...since im blending still, is still a bit cheaper than gas). the addition of a little e85 doesnt destroy miliage, wereas running it straight certainly does. ill break roughly even between 91 oct and e85 $$ wise when the conversion is complete. my current fueling setup does not support more than a 70% mix of e85 to 30% SUMMER BLEND (e0) gas mix. after that, im fresh out of fueling ability and right into ECU enduced soft-limp mode (lean mixture code).

this conversion is a fun process and there is certainly more to come when a few obstacles are overcome....a cant reitterate enough that this is not a $$ thing, but a performance thing. being able to affordably run a race file 24/7 is fun! there are other performance factors based upon the increased consumption of e85, and its inherrent lesser energy that i did not expect...much lower EGTs overall and especially at WOT for repeated pulls....temps really low! intercooler efficiency as a result is also drastically increased driving IATs down even in the hottest temps weve seen yet this year.

all in all, fun stuff....but i would not advocate going to the pump and just filling a bit in...we have been logging and monitoring this for well over a month....i mean hourse of logs and part throttle, WOT, and averything in-between logging to accumulate data....data that at the end of the day only applies to my specific setup! people with different pieces of hardwars, and certainly software may see differeent results...so i would say those with the desire to experiment but without the patience of Jobe would be ill advised to do so.

Can you please explain why your intercooler now works more efficiently? That makes no sense to me.

with less heat in the overall system (EGT sub 840 deg. C) and less IAT fluctuation, this implies that the intercooler is actually performing better...i.e. it isnt getting heat soaked as it normally would on pump gas. of course there are many othe processes at work, of which that is one.

whereas my IC was far less effective on pump gas, and as a result, the typical dyno pulls woulf have tangible torque and HP variences between pulls where no extensive cooling efforts were made, this is not the case here. if you look at those dyno plots, their varience is insignificant. they were taken less than 5min apart with no external cooling other than MAC's crappy fans. this implies that not only is the whole system running cooler (which it is) but that the ICs are not as taxed as they have been previously (that they are able to recover quickly and are not as subject to heat-soak). Up here at this elevation, DSMIC setups for the B6 1.8t are not generally as effective as their FMIC counterparts due to air densitly (or lack thereof).

now i did make a blanket statement specifically about the intercooling...but i do wholely recognize that there are vast differences in the overall system performance...as i have been logging now for over 1 month. just about everything works better on this fuel.

with less heat in the overall system (EGT sub 840 deg. C) and less IAT fluctuation, this implies that the intercooler is actually performing better...i.e. it isnt getting heat soaked as it normally would on pump gas

Lower EGTs and less IAT fluctuation does not imply the intercooler is working more efficiently. The only thing that would improve IC performance is a change to the intercooler.

The octane boost would be fun and perhaps provide a nice safety margin for boosted cars, assuming it'll idle OK with injectors big enough to handle the flow.

-Joel.

it really depends on the car. many flex-fuel vehicles aren't great at running either gas or e85, but do ok with both, others are better at one or the other....very application specific. it is inevitable that when running e85, miliage overall will decrease.

so far we aren't sure exactly where mine will stand when done with the conversion. running a 70% e85, 30% gas (55% ethanol by volume), my part-throttle fuel trims vary on average between 10-15% increase (this is, of course, an average), at WOT im sure its more, but most of my driving its part throttle, so that is a fairly good benchmark. What i have found so far is that there is not a "steady" increase by parts ethanol added to gas, but rather that the more eth i run, exponential increases in fuel are needed. given that 70% e85 blend is as good as my current fueling can do, its hard to say where the overall miliage decrease will be....but im guessing roughly 25% overall decrease in fuel economy.....about the same as pumping 91oct $$wise currently.

the math doesnt even begin to sway at e85 being more pricey when looking in terms of race gas prices however! as far as my logs go, the car is actually doing better performance-wise than it would have running 100oct unleaded race fuel, and comparably to 114 lead i have logged lately.

E85 contains 72.5% of the energy that is contained in gasoline (91 oct). If your car currently gets 30 miles per gallon (MPG) you could expect to see drop in mileage proportional to difference in energy between the two fuels which would be about 22 MPG on E85 or a drop of 27.5%.

When you convert your car from gasoline to E85 you are not increasing the efficiency of your car, so it is going to still require the same amount of energy to go down the road and accelerate which means using more fuel.

One advantage for forced induction (turbo charged and super charged) engines is running on E85 allows you to run higher levels of boost since the auto ignition point (detonation) of E85 is much higher then gasoline. You could actually remove or not use an inter-cooler in most cases where you are running 20 psi of boost which would increase the volumetric (pump) efficiency of the engine. There have been cars in California for years running on M85 (85% methanol, 15% gasoline) with turbos running very high boost levels (30-35 psi) without a problem.

E85 contains 72.5% of the energy that is contained in gasoline (91 oct). If your car currently gets 30 miles per gallon (MPG) you could expect to see drop in mileage proportional to difference in energy between the two fuels which would be about 22 MPG on E85 or a drop of 27.5%.

When you convert your car from gasoline to E85 you are not increasing the efficiency of your car, so it is going to still require the same amount of energy to go down the road and accelerate which means using more fuel.

One advantage for forced induction (turbo charged and super charged) engines is running on E85 allows you to run higher levels of boost since the auto ignition point (detonation) of E85 is much higher then gasoline. You could actually remove or not use an inter-cooler in most cases where you are running 20 psi of boost which would increase the volumetric (pump) efficiency of the engine. There have been cars in California for years running on M85 (85% methanol, 15% gasoline) with turbos running very high boost levels (30-35 psi) without a problem.

One advantage for forced induction (turbo charged and super charged) engines is running on E85 allows you to run higher levels of boost since the auto ignition point (detonation) of E85 is much higher then gasoline. You could actually remove or not use an inter-cooler in most cases where you are running 20 psi of boost which would increase the volumetric (pump) efficiency of the engine. There have been cars in California for years running on M85 (85% methanol, 15% gasoline) with turbos running very high boost levels (30-35 psi) without a problem.

I have a hard time swallowing the current belief that E85 REALLY costs over $2/gal. to make.

it helps that the US Gov't is providing some subsidies to aid in the production and refinement of the product. This was hidden in one the other bills that got passed a couple years back. It was put thru as a rider for alternative energy, i forget what the original bill (main bill topic) was about. But this slipped thru. It wasn't expected to be as big as it is now. IIRC the subsidies are expected to run out in 2010-11 unless they are reinstated.